The present invention relates generally to prosthetic devices and particularly to a prosthetic device for persons suffering a condition known as "drop foot."
Individuals afflicted with drop foot, also sometimes referred to as "foot drop", do not have full control over muscles that raise and lower the foot. Most troublesome is an inability to raise the foot when walking. The condition compromises the nerves normally conducting electrical impulses from the brain resulting in signal blockage either entirely or occasionally without warning. The toe of the foot often cannot be positioned to clear the ground as the person walks along. Consequently, the person's toe or inside edge of the foot drags on the ground while walking. The afflicted individual thereby experiences, sometimes spontaneously, an inability to walk, an inability to walk in normal fashion, or a risk of potential injury by stumbling and falling while attempting to walk.
A variety of devices have been proposed to aid the person in overcoming this condition, i.e., apparatus secured to the leg and ankle and to the shoe to prevent tripping or stumbling or dragging the foot while walking. Unfortunately, none of these devices are popular for their bulky, heavy, cumbersome, and uncomfortable aspects. Most such devices are difficult to mount and dismount and present significant inconvenience to persons wishing to temporarily remove the device when not needed, i.e., when not walking or when relaxing in particular postures including sitting positions where one desires more complete flexibility of the ankle to achieve a comfortable position. Finally, all of these devices lack significant concealment features and manifest themselves to the user and to others as bulky contraptions when in use.
U.S. Pat. No. 3,916,886 issued Nov. 4, 1975 to Rogers, et al and entitled "Preformed Self-Conforming Drop Foot Brace" shows a rigid structure running from the calf muscle down the back of the leg, around the heel, and under the foot. This structure restricts the foot to a 90 degree maximum extension. In other words, the person cannot point their toe out to form a greater than 90 degree angle between the leg and foot. In this restricted range of movement, the toe cannot drop and drag upon the ground and the person avoids potential embarrassment or injury when walking. The drop foot brace by Rogers, et al thereby solves the problem of drop foot when walking. Unfortunately, this device is severely uncomfortable and restrictive especially when not walking. It is only useful when swinging the foot forward in walking and interferes with all three aspects of walking. It is like walking while wearing ski boots. It is not suitable for sitting or relaxing in a sitting posture such as with a bent ankle or relaxed foot extending outward in a other than 90 degree angle.
U.S. Pat. No. 4,651,723 issued Mar. 24, 1987 to Cowalk and entitled "Drop Foot Splint" includes a ringed leather brace encircling completely the user's ankle and including a forward and downward extension from the front of the brace down into the top of the shoe. This device is extremely uncomfortable because of the need to securely attach the brace around the leg and establish a rigid coupling between the brace and the person's leg to adequately lift the foot through the extension engaging the shoe.
U.S. Pat. No. 1,598,504 issued Aug. 31, 1926 to Pierce, et al and entitled "Ankle Brace" shows a brace attaching around the lower portion of the user's leg with a structure extending downward along the back of the leg and including a hinged coupling to a structure attached to the user's shoe, i.e., the rear of the shoe heel. The contemplated use of this brace, however, is to aid in skating and not in lifting the foot, i.e., there is no need or desire to include any active mechanism to participate in foot movement. Rather, the device is used as a fortification against lateral bending of the ankle and potential injury during a sports activity.
U.S. Pat. No. 2,874,690 issued Feb. 24, 1959 to Cowgil and entitled "Orthopedic Foot Drop Brace" shows a structure engaging the heel of the shoe and extending upward to engage the rear of the leg just above the shoe.
It would be desirable, therefore, to provide a drop foot brace establishing aid against drop foot, but also allowing for comfort and flexibility as desired when sitting or relaxing, for more convenient use in attachment and removal and for concealment when in use.